FOT

Abbreviation for frequency of optimum transmission . In the transmission of radio waves via ionospheric reflection , the highest effective, i.e., working, frequency that is predicted to be usable for a specified path and time for 90% of the days of the month. ( 188 ) Note 1: The FOT is normally just below the value of the maximum usable frequency (MUF). In the prediction of usable frequencies, the FOT is commonly taken as 15% below the monthly median value of the MUF for the specified time and path. Note 2: The FOT is usually the most effective frequency for ionospheric reflection of radio waves between two specified points on Earth. Synonyms frequency of optimum traffic , optimum traffic frequency, optimum transmission frequency, optimum working frequency.